Unit 3 Questions MEGATHREAD :)

[luken93]

Just got kinda owned by NEAP 2010, so I have a question:

Can someone please clarify the Primary, Secondary and Tertiary Structure of DNA/Proteins.

Is it the following:
DNA
Primary = Sequence of nucleotides along a single strand, hence the bond is between the Phosphate/Deoxyribose Sugars
Secondary = The complementary Base Pairing between the two strands, hence the bonding is hydrogen bonding between AT and GC
Tertiary = The ionic bonding that occurs between the negatively charged Phosphate Groups and the positively charged histones, allowing for it to be super-coiled.

Proteins
Primary = The sequence of Amino Acids, bonded together covalently by Peptide Linkages (CO-NH)
*Secondary = The coiling, bending or folds of the chain that are caused by Hydrogen Bonding between carboxyl and amine groups along the chain (bonding isn't on the adjacent amino acid, but one that is pulled close when coiled)
*Tertiary = Affected by the side chains of amino acids, and can be formed/modified by hydrogen bonding (between CO-HN), covalent bonding (between S-S creating a disulfide bridge), and ionic bonding (between NH2 and COOH)

*I don't think these are entirely correct, so any opinions would be appreciated

[VivaTequila]

How is it that sulfuric acid actually works as a dehydrating agent in Fischer esterifications? I don't understand how the dehydrating aspect of it is what makes the equilibrium slam to the product side, or how the dehydrating aspect works (the water is still all in the solution... I think it has to do with the removal of product, but why would that actually entice the reaction to go further...

wow at below

[TortMequila]

Be helpful or don't post

[luken93]

Okay, so I have an annoying problem I'd like to rectify. \

When a question gives you a mixture and they ask you whether GLC/HPLC would be more appropriate, is there an easy way to knowing this?
I know that HPLC is used for substances that usually have an Mr > 300, and may decompose upon heating.
But if you are presented with say perfume, how do you know which to use?

Is it more logic than anything of what is in it?

[Graphite]

Think about which one is used for volatile liquids which perfume is.

[luken93]

Think about which one is used for volatile liquids which perfume is.

Yeah, but HOW do you know it is a volatile liquid is more what I'm asking..

[Graphite]

Volatile liquids are strong smelling

[Graphite]

It makes sense if the substance is volatile, it would evaporate into your nose

[luken93]

It makes sense if the substance is volatile, it would evaporate into your nose

That's actually a really good way of putting it!
However, I assume it's not limited to only substances you can smell?

[jane1234]

It makes sense if the substance is volatile, it would evaporate into your nose

That's actually a really good way of putting it!
However, I assume it's not limited to only substances you can smell?

No, a volatile substance is any one that readily gives off a gas.

[Zebra]

for writing the states for reactants and products... do we have to remember the solubility rules?
Obviously there are some straight forward ones but sometimes I struggled with some compounds!

[Graphite]

It makes sense if the substance is volatile, it would evaporate into your nose

That's actually a really good way of putting it!
However, I assume it's not limited to only substances you can smell?

No, a volatile substance is any one that readily gives off a gas.

I described a property of volatile liquids. They do evaporate more easily based on the weak interactions at the surface of the liquid therefore evaporate => a gaseous phase.

[jackson1234]

When writing esterification/condensation reactions, why are all the products in liquid state rather than gaseous ?

[pi]

for writing the states for reactants and products... do we have to remember the solubility rules?
Obviously there are some straight forward ones but sometimes I struggled with some compounds!

Yep, you should know them (and most common exceptions)

[luken93]

for writing the states for reactants and products... do we have to remember the solubility rules?
Obviously there are some straight forward ones but sometimes I struggled with some compounds!

Yep, you should know them (and most common exceptions)

Has anyone good a decent summary of the "common exceptions"?
Would be handy

Moderator action: removed real name, sorry for the inconvenience